In the related art, there are known medical manipulators provided with an elongated inserted portion that can be inserted into a body for treating the body interior by remotely manipulating, from outside the body, a treatment tool installed in the inserted portion (for example, see Patent Literature 1). The inserted portion of such a manipulator is provided with a bending portion for changing the direction that a distal-end surface faces, in which a camera, a treatment tool, and so forth are installed.
In addition, in order to precisely control the bending angle of the bending portion, a gear mechanism is employed as a main bending mechanism for bending the bending portion. Specifically, the employed configuration is such that the bending portion is bent by converting a large rotational motion of a shaft generated at the basal end of the inserted portion to a small linear motion by means of a threaded shaft that rotates together with the shaft and a nut fastened to the threaded shaft, and by utilizing this linear motion to push and pull a wire connected to the distal end of the inserted portion.
In the inserted portion employing such a gear mechanism, in order to generate a rotational motion of the shaft from the linear motion of the wire, it is necessary to linearly move the wire with a sufficiently large external force. In other words, the shape of the bending portion bent by pushing and pulling the wire is sufficiently stable against an external force.
On the other hand, in order to switch to a state in which the bending portion is flexible and bent in accordance with the external force from a state in which the bending portion is rigid and the same angle is maintained against the external force, a clutch that is provided between the gear mechanism and the wire and that can separate them from each other is employed (for example, see Patent Literature 2).